Imaging lens

摘要

A compact, low-profile, low-cost imaging lens with brightness of F-value 2.5 or less and a wide field of view, which corrects aberrations properly. Elements are arranged from an object side: an aperture stop, positive first lens having a convex object-side surface, negative biconcave second lens having concave object-side and image-side surfaces, positive or negative third lens having a convex object-side surface and at least one aspheric surface; positive meniscus double-sided aspheric fourth lens having a convex image-side surface; and negative double-sided aspheric fifth lens having a concave image-side surface. The fifth lens' aspheric image-side surface has a pole-change point off an optical axis, and the imaging lens satisfies the following conditional expressions:
TTL/2ih≦0.8   (1)1.60

主权项

1. An imaging lens which forms an image of an object on a solid-state image sensor and provides brightness with an F-value of 2.5 or less, in which elements are arranged in order from an object side to an image side, comprising:
an aperture stop; a first lens having positive refractive power and a convex surface on the object side; a second lens having negative refractive power and a concave surface on the image side; a third lens having positive refractive power, a convex surface on the object side, a concave surface on the image side and at least one aspheric surface; a fourth lens as a meniscus double-sided aspheric lens having positive refractive power and a convex surface on the image side; and a fifth lens as a double-sided aspheric lens having negative refractive power, a concave surface on the object side and a concave surface on the image side, wherein the aspheric image-side surface of the fifth lens has a pole-change point off an optical axis, and conditional expressions (1) and (10) below are satisfied:
TTL/2ih0.8   (1)1.98≦r7/r8<3.0   (10) where TTL: total track length ih: maximum image height r7: curvature radius of the object-side surface of the fourth lens r8: curvature radius of the image-side surface of the fourth lens.